A fluoropolymer (hereinafter referred to also as a fluororesin) such as polytetrafluoroethylene, a tetrafluoroethylene/perfluoro(alkyl vinyl ether) type copolymer or an ethylene/tetrafluoroethylene type copolymer, is excellent in e.g. heat resistance, chemical resistance, oil resistance, weather resistance, gas barrier properties, fuel barrier properties, release properties, non-tackiness and antifouling properties, and it is employed in various fields such as semiconductor industries and automobile industries. Along with the expansion of its use, in a case where improvement in mechanical strength of the fluororesin, cost down or the like is required, a multilayer laminate of a fluororesin and e.g. a thermoplastic resin other than the fluororesin, which is excellent in mechanical strength, has been studied.
Particularly, a fuel transfer hose for automobiles is required to have fuel barrier properties, fuel oil resistance, mechanical strength and the like, and therefore a multilayer laminated hose has been proposed, in which a fluororesin having excellent fuel barrier properties and fuel oil resistance is used as an internal layer and polyamide having excellent mechanical strength is used as an external layer (e.g. JP-A-2-107371 and JP-A-5-8353). In order to meet reinforcement of regulations against emission gas in the future, a multilayer laminated hose has been proposed, in which an interlayer of a thermoplastic resin having remarkably excellent fuel barrier properties is interposed between a fluororesin and a polyamide (e.g. JP-A-2003-127256 and JP-A-2000-329266). The thermoplastic resin constituting the interlayer may, for example, be polyphenylene sulfide, polyethylene terephthalate, polybutylene terephthalate or polyethylene naphthalate. However, such a multilayer laminated hose is insufficient in adhesive strength between the fluororesin layer and the thermoplastic resin layer as an interlayer.
Further, a multilayer laminated film made of a fluororesin and a thermoplastic resin is well known (e.g. JP-A-2002-67241 and JP-A-2001-138338), and its application to e.g. a release film has been proposed. However, said multilayer laminated film is produced by a process wherein the surface of a fluororesin film is subjected to corona treatment, then an adhesive is applied thereto, and then a thermoplastic resin film is laminated thereon, and thus, its productivity is not high.